Congratulations on the job offers!
When I first considered moving to Thailand in 2011, I read all of the cost of living numbers but I just couldn't quite believe it: how can someone live on $1k per month?
Then I moved there, and it became clear: it really is far cheaper for (almost) everything with (almost) the same quality.
Bangkok is a five star city, and you could spend $300,000 per year if you want to. (Not true everywhere.) But, you won't need to spend so much, and even spending $100,000 will be a challenge.
In general, you can trust the cost of living estimates, and if you double them you'll likely have more than you can imagine.
The biggest hidden costs will be premium goods that only foreigners enjoy: foods labeled organic, imported foods, michelin restaurants, high end gyms, private schools, and new cars.
The business climate isn't the easiest, as the government overall is not friendly to expats. Most freelancers in your situation would avoid a Thai business structure, which you only really need if you want business clients in Bangkok.
In general, I'd keep these things in mind, and you'll be fine:
- Its hot and balmy
- Street food is remarkably good and safe to eat.
- The area around Terminal21 is expensive for Bangkok, but a great place to start. I'd consider a hotel near there until you get your bearings. The Westin Grande is a five star hotel for $100 per night, for example. Thats within your budget, so I'd start there for a week and then explore lower end accommodations until you find the right value.
- Uber is available
Hope that helps!